Transition metals and their compounds are widely used as catalysts in industry. Explain why transition metals are able to act as catalysts, and state TWO other properties of transition metals that make them useful in everyday applications.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Transition metals such as iron, copper and nickel are found in the d-block of the periodic table. They have a number of characteristic properties that distinguish them from other metals.
Model answer (5 marks)
Transition metals can have variable oxidation states, allowing them to accept and donate electrons during a reaction. This electron transfer enables the metal to form temporary bonds with reactant molecules, providing an alternative reaction pathway that lowers the activation energy. The catalyst is not consumed and remains chemically unchanged at the end of the reaction.
Other useful properties of transition metals are:
1. High melting point.
2. Good electrical conductivity.
Other useful properties of transition metals are:
1. High melting point.
2. Good electrical conductivity.
Examiner tips
- Use the word ‘variable oxidation states’ or ‘variable valency’ to show understanding of the catalytic mechanism. Show that the catalyst is not consumed. State two distinct properties from the list (e.g. high melting point and good conductivity).
Common mistakes
- Confusing variable oxidation states with a single fixed oxidation state. Failing to mention that the catalyst is not used up. Listing the same property twice or giving a property not in the provided list.
Mark scheme (5 marks)
- Transition metals can have variable oxidation states (accept: variable valency)
- This allows them to accept and donate electrons during a reaction, enabling them to form temporary bonds with reactant molecules / providing an alternative reaction pathway
- The catalyst is not used up / remains chemically unchanged at the end of the reaction
- One correct property stated — e.g. high melting point / high density / good conductor of electricity / high tensile strength
- A second correct and different property from the list above
Key terms in this question
Related
- All Edexcel A-Level Chemistry (9CH0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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